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Stress relaxation
About: Stress relaxation is a research topic. Over the lifetime, 12959 publications have been published within this topic receiving 270815 citations.
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TL;DR: In this paper, the authors applied crystal plasticity to model the cyclic constitutive behavior of a polycrystalline nickel-based superalloy at elevated temperature using finite element analyses.
72 citations
TL;DR: Weakly flocculated, thixotropic suspensions have been investigated by means of fast stress jump experiments to determine the elastic and hydrodynamic contributions to the shear stress and it is shown that the data agree qualitatively with the model proposed by Potanin et al.
72 citations
TL;DR: In this article, the authors measured the dynamical mechanical properties of human red blood cells with optical tweezers and found a power-law decay of the stress as a function of time, down to a plateau stress, and a power law increase of the cell's elasticity.
Abstract: We measure the dynamical mechanical properties of human red blood cells. Single cell response is measured with optical tweezers. We investigate both the stress relaxation following a fast deformation, and the effect of varying the strain rate. We find a power law decay of the stress as a function of time, down to a plateau stress, and a power law increase of the cell's elasticity as a function of the strain rate. Interestingly, the exponents of these quantities violate the linear superposition principle, indicating a nonlinear response. We propose that this is due to breaking of a fraction of the crosslinks during the deformation process. The Soft Glassy Rheology Model accounts for the relation between the exponents we observe experimentally. This picture is consistent with recent models of bond remodeling in the red blood cell's molecular structure. Our results imply that the blood cell's mechanical behavior depends critically on the deformation process.
72 citations
TL;DR: In this article, the authors studied the relaxation of compositionally graded InGaAs buffers, with and without uniform cap layers, and the effects of different cap layers on the relaxation behavior of the graded buffer has been studied by double crystal x-ray diffraction, TEM, and low temperature photoluminescence.
Abstract: The relaxation of compositionally graded InGaAs buffers, with and without uniform cap layers, has been studied. Simple InGaAs linear‐graded layers on GaAs substrates never reach complete relaxation. The residual strain in these structures produces a dislocation‐free strained top region while the rest of the buffer is nearly completely relaxed through misfit dislocations, as observed by transmission electron microscopy (TEM). This strained top region is analyzed and its thickness compared with theoretical calculations. The effects of different cap layers on the relaxation behavior of the graded buffer has been studied by double crystal x‐ray diffraction, TEM, and low temperature photoluminescence, and results compared with predictions of the models. The optical quality of the cap layer improves when its composition is close to the value that matches the lattice parameter of the strained surface of the grade. The design of linear graded buffers having a strain‐free cap layer with high crystalline quality is...
72 citations
TL;DR: In this article, the effects of amount and dispersion of MWCNTs on mechanical, thermal and rheological properties of polypropylene (PP) nanocomposites were examined with various characterization methods and test procedures, in detail.
Abstract: In this study, multi-walled carbon nanotube (MWCNT) filled polypropylene (PP) nanocomposites prepared by melt processing methods by employing extruder and injection molding techniques were examined with various characterization methods and test procedures, in detail. Aim and novelty of the work were to merely investigate the effects of amount and dispersion of MWCNTs on mechanical, thermal and rheological properties of PP including no compatibilizer and thus chemical interaction and/or interfacial adhesion effect. The mechanical test results showed that the incorporation of MWCNTs increased the tensile strength (18.4%), flexural strength (35.2%) and modulus of elasticity (45%) while it decreased the impact strength (18%) and elongation at break (690%) values of PP/MWCNT nanocomposites. Thermal analysis data revealed that the MWCNT addition slightly increased the crystallization peak onset and peak maximum temperatures of PP under non-isothermal conditions. Frequency-dependent melt rheological behaviors of nanocomposites in linear viscoelastic regime pointed out that the storage modulus (G'), loss modulus (G''), complex viscosity (η*), and relaxation time of PP increased with the increasing amount of MWCNT. Non-linear rheological tests such as creep and stress relaxation also depicted that nanocomposites exhibited lower creep strain and relaxation rate than PP. Based on the thermal and mechanical test results, 0.3 wt% of MWCNT could be considered as the critical filler amount also called as “percolation threshold” for improving the solid-state physical properties of PP/MWCNT nanocomposites under the circumstances of no compatibilizer.
72 citations